1. Field of the Invention
The present invention relates to carrier class switches, and in particular, to a method and apparatus for providing multimedia and multirate switching in an integrated carrier-class switching platform.
2. Description of the Related Art
Most conventional switches are adapted for switching traffic of a specific media such as voice switches (e.g. 4ESS, DMS200) and data switches (e.g. ATM/Frame Relay), or for switching traffic of a specific speed such as backbone switches (switching traffic among broadband interfaces, e.g. OC-12) and access switches (switching traffic among narrowband interfaces, e.g. DS0).
In particular, a backbone switch typically includes a switching fabric that switches between a certain number (e.g. 8 or 16) of high speed ports such as OC-12 ports. In contrast, low speed traffic is generally switched between low speed ports in an access switch having, for example, a shared bus architecture. For such low speed traffic to access one of the high-speed lines coupled to the switching fabric (and vice-versa), access switches generally include an uplink module to convert the low-speed traffic to high-speed traffic, and a separate OC-12 line is needed to transmit the converted low-speed traffic to the high-speed switching fabric. Such methods typically require one high-speed port to be dedicated for each low-speed uplink connection, thus wasting the available bandwidth on the high-speed port.
Moreover, traffic can typically be switched within one type of network. For example, ATM traffic can only be switched among ATM networks, IP traffic can only be switched among IP networks, etc.
Accordingly, there remains a need in the art for an integrated switching apparatus that provides for switching among both low speed ports (e.g. NxDS0) and high speed ports (e.g. OC-3). Moreover, such a switching apparatus should be able to minimize the traffic loss due to rate mismatch during the burst period.
There further remains a need in the art for a switch apparatus that provides for switching among different types of multimedia streams. Such a switching apparatus should also be able to guarantee the quality of service for the different media types, e.g. voice, video, data.
Accordingly, an object of the present invention is to provide a switching apparatus and methodology that permits traffic of any speed to be switched between ports of a single device.
Another object of the present invention is to provide a switching apparatus and methodology that permits traffic of any media to be switched in a single device.
Another object of the present invention is to provide a switching apparatus and methodology that minimizes traffic loss due to rate mismatch between narrowband and broadband connections during the burst period.
Another object of the present invention is to provide a switching apparatus and methodology that guarantees quality of service for flows of various media types.
To achieve these objects and others, the switch apparatus and method according to the invention implements a three stage switching process. Various types of media streams presented to the switch apparatus via broadband and narrowband flows (e.g. voice/fax call, video session, packet flow between source and destination ports, etc.) are converted to ATM cells and enqueued in corresponding virtual circuit (VC) queues. ATM cell switching is performed among the different cards based on the quality of service required for each virtual circuit. The switched ATM cells are then converted to the outgoing media types and outputted to the necessary broadband and narrowband flows. The switch apparatus and method are further adapted to perform rate shaping and traffic management so as to guarantee the quality of service for various media types (voice, video, data) and also minimize the traffic loss due to rate mismatch between narrowband and broadband connections during the burst period. By virtue of this implementation, the switch apparatus and method of the present invention can perform any-to-any media type switching.